A workpiece chuck can be used to hold workpieces such as semiconductor wafers during processing and testing. Because integrated circuits formed in a wafer under test are commonly tested over temperature, the workpiece chuck can include a temperature control system for controlling the temperature of the wafer during testing. As integrated circuits become smaller and more densely integrated, positioning tolerances for testing systems such as wafer probers decrease. With very small positioning tolerances, it is very important that the chuck supporting the wafer during testing be mechanically stable. This requirement is especially challenging in a temperature-control chuck where the chuck must maintain mechanical and electrical stability over a wide range of temperatures. At temperature extremes, particularly at high temperatures, conventional wafer chucks tend to distort due to thermal expansion and contraction and the integrity of the materials of which the chucks are constructed. For example, chucks made of softer materials will tend to distort at high temperature. This problem is exacerbated by the increasing mechanical loads on the chuck introduced by the test system, i.e., the wafer prober.